1. Field of the Invention
This invention relates to an oil transporting vaporizer having particular application for use in a “smoke” generating apparatus and including a hollow tube body that is ideally manufactured from a high temperature, fire-resistant, porous material, such as ceramic, to transport oil from a reservoir thereof to a heater wire that is wound around the tube body. Oil being transported through and over the tube body is vaporized into smoke by the beater wire for delivery to a (e.g., closed fluid) system under test for leaks.
2. Background Art
Smoke generating apparatus are known for generating a visible aerosol mist to be delivered to a fluid system undergoing testing for leaks. While such apparatus are commonly described as smoke machines, it is preferable that the “smoke” be a non-toxic aerosol mist produced by evaporation and condensation at controlled temperatures rather than actual smoke which is a product of partial combustion and tends to contain toxic combustion byproducts. Hence, in the preferred embodiment to be described below, “smoke” refers to a visible aerosol mist, gas, vapor or combination thereof. Some systems that are ideal for leak testing by means of the aforementioned smoke generating apparatus are used for a motor vehicle. By observing any visible aerosol mist which exits a small and often visually imperceptible hole in the system under test, an indication is provided to the observer of the presence and location of the leak so that a repair might be made.
One example of a particular smoke producing apparatus for use in detecting leaks in a fluid system is described in U.S. Pat. No. 7,305,176 issued Dec. 4, 2007. Such a smoke producing apparatus includes a fluid transfer device which conveys a petroleum-based oil from an oil reservoir to the vicinity of a beating element so that the oil can be vaporized into smoke. The fluid transfer device described in U.S. Pat. No. 7,305,176 is generally a woven stranded fiberglass wick that is adapted to convey a supply of oil from the oil reservoir to the heating element primarily by means of capillary action to produce smoke when the heater element is energized. The fiberglass wick is described as being able to withstand temperatures as high as 1000° F.
However, the woven fiberglass wick used in the conventional smoke producing apparatus described above may ignite and burn at temperatures above 1000° F. or its fiber structures may deteriorate and melt together at temperatures below 1000° F. Consequently, at operating temperatures above 1000° F., this smoke producing apparatus could be damaged and/or the fiberglass wick may require replacement. What is more, repeatedly wetting the strands of the woven fiberglass wick with oil and subjecting the strands to thermal stress may ultimately cause the wick to tail over time so as to further necessitate replacement. Transferring oil from the reservoir to the beater element associated with the stranded fiberglass wick primarily by means of capillary action is a relatively slow process which can delay as well as limit the production of smoke. Further, the rate at which oil is transferred from the reservoir to the heater element associated with a stranded fiberglass wick primarily by means of capillary action occurs at a fixed rate for a given wick and diminishes as the wick ages. This limits the flexibility of a smoke generating apparatus which is unable to adjust its smoke delivery rate as may be required for larger or smaller test systems.
Accordingly, what is desirable is an improved oil transport and vaporizing device for use in a smoke generating apparatus, wherein the conventional capillary wick like that described above is replaced by the improved device wherein the improved device is adapted to enhance oil transport from the oil reservoir to the heating element within a time and in an amount that will improve the efficiency by which the oil is vaporized to smoke to be delivered to the system being tested for leaks, resist burning at temperatures above 1000° F., and resist deterioration at sustained temperatures below 1000° F. By virtue of the foregoing, the structural integrity of the improved device can be preserved following frequent periods of being immersed in oil and transporting the oil to die heating element so as to overcome the need for frequent replacements common to the wick-type capillary device and thereby reduce the down time of the apparatus. It is also desirable to be able to control the delivery of oil to the heating element of the improved oil transport and vaporizing device as well as die energization of the hearing element such that the production efficiency of smoke is optimized while any overheating and degradation of the oil is minimized. Further, it is desirable that the improved oil transport and vaporizing device be capable of operating at variable pressures so that the production and delivery of variable amounts of smoke can be correspondingly controlled, it is still farther desirable that the improved oil transport and vaporizing device be able to produce smoke with a narrow range of oil droplet diameters which have an optimum size for the system being tested.